I wouldnt recommend going any lower than 4.5 grains on the bullseye and no lower than 5.4 grains on the unique. you might be risking a squib load if you do. the grain weights I stated are start charges and yes they would be relatively light. probably pushing for either charge around 700 fps. if ya want a real light load I suggest using hodgdon clay with it you can load down to as low as a 670 fps with 3.7 grains clays